Method and assembly for bonding metal layers in a gas turbine engine using a polyimide adhesive

Abstract

A method and system is described herein for using a polyimide adhesive to bond a first metal layer to a second metal layer used in a gas turbine engine. The polyimide adhesive may be a film or a paste and is able to withstand operating temperatures in excess of 600 degrees Fahrenheit (315 degrees Celsius). In an exemplary embodiment, the second metal layer is an outer face skin of an exhaust nozzle and the first metal layer is a metal doubler configured to cover a damaged portion of the outer face skin. In some embodiments, the first and second metal layers may be formed of titanium.

1 . A method of bonding two metal layers used in a gas turbine engine, the method comprising:
 applying a polyimide adhesive to a first metal layer configured to be used in a gas turbine engine;   applying the polyimide adhesive to a second metal layer configured to be used in the gas turbine engine such that the polyimide adhesive is sandwiched between the first metal layer and the second metal layer; and   curing the polyimide adhesive to bond the first metal layer and the second metal layer.   
   
   
       2 . The method of  claim 1  wherein at least one of the first metal layer and the second metal layer is titanium. 
   
   
       3 . The method of  claim 1  wherein the second metal layer is a face skin having a damaged area. 
   
   
       4 . The method of  claim 1  wherein a thickness of the first metal layer is between approximately 0.25 and 0.51 millimeters. 
   
   
       5 . The method of  claim 1  wherein the polyimide adhesive is selected from a group consisting of a film and a paste. 
   
   
       6 . A repair assembly for repairing a metal part used in a high temperature region of a gas turbine engine, the repair assembly comprising:
 a metal doubler configured to cover a damaged area of the metal part; and   a polyimide adhesive configured to attach the metal doubler to the metal part.   
   
   
       7 . The repair assembly of  claim 6  further comprising a curing device to bond the metal doubler to the metal part. 
   
   
       8 . The repair assembly of  claim 6  wherein the polyimide adhesive is selected from a group consisting of a film and a paste. 
   
   
       9 . The repair assembly of  claim 6  wherein the metal doubler is titanium. 
   
   
       10 . The repair assembly of  claim 6  wherein the metal doubler has a thickness between approximately 0.25 and 0.51 millimeters. 
   
   
       11 . The repair assembly of  claim 6  wherein the part is exposed to temperatures equal to or greater than about 315 degrees Celsius. 
   
   
       12 . The repair assembly of  claim 6  wherein the metal part is an exhaust nozzle formed from a honeycomb structure and a face sheet, and the damaged area includes a tear in the face sheet. 
   
   
       13 . The repair assembly of  claim 12  wherein the face sheet has a thickness between approximately 0.25 and 0.51 millimeters. 
   
   
       14 . The repair assembly of  claim 6  wherein the polyimide adhesive has a thickness between approximately 0.08 and 0.38 millimeters. 
   
   
       15 . A method of repairing a part used in a gas turbine engine and having a damaged metal face skin, the method comprising:
 preparing a metal foil configured to cover a damaged area of the metal face skin of the gas turbine engine part;   attaching the metal foil to the damaged area of the metal face skin using a polyimide adhesive; and   curing the polyimide adhesive to bond the metal foil to the metal face skin.   
   
   
       16 . The method of  claim 15  wherein the polyimide adhesive is a film and preparing the metal foil includes attaching the polyimide adhesive to the metal foil. 
   
   
       17 . The method of  claim 16  wherein preparing the metal foil includes freezing the metal foil after attaching the polyimide adhesive to the metal foil and prior to attaching the metal foil to the metal face skin. 
   
   
       18 . The method of  claim 15  wherein the polyimide adhesive includes at least one of a film and a paste. 
   
   
       19 . The method of  claim 15  wherein the gas turbine engine part is an exhaust nozzle. 
   
   
       20 . The method of  claim 15  wherein the gas turbine engine part operates at temperatures greater than or equal to 315 degrees Celsius.